Hobbymat 65 Part 2 (Turning under electrical power)

Hobbymat MD65 Mill Lathe conversion to electrical drive and threading using electronic leadscrew.
All parts except electronic lead screw and some bearings sourced from Ebay
Electronic lead screw (French design) CNCTronic
electroniclead...
www.youtube.co...
Z axis mill
Z axis motor
DC 24V Speed Torque Reversible Electric Gear Motor Adapter Gearmotor 45W 260RPM
£55.99
60A PWM Brushed DC Motor Speed Controller CW CCW Reversible Switches 12V/24V/48V
£11.12
Z axis spindle
500W 24V DC electric brush motor for scooter bike go-kart minibike New ZY1020500W 24V DC £43.28
PWM speed controller
40A 9-50V DC 12V-48V 2000W Motor Speed Control Module PWM HHO RC Controller UK
£12.58
Bearings
2 X 7205B angular contact bearings
2X 6005-2RSH deep groove bearings
1X 6204 2RS deep groove bearing
Lathe Spindle
500W 24V DC electric brush motor for scooter bike go-kart minibike New ZY1020500W 24V DC £43.28
PWM speed controller
40A 9-50V DC 12V-48V 2000W Motor Speed Control Module PWM HHO RC Controller UK
£12.58
Bearings from Simply Bearings
7305 BEP single row angular contact bearing
25X62X17mm
7206 BEP Single row angular contact bearing
30X62X16mm
X axis stepper
STEPPERONLINE Nema 23 Stepper Motor 3Nm 4.2A 113mm High Torque Φ10mm CNC Router
£29.50
X axis stepper driver
STEPPERONLINE Nema 34 Stepper Motor Driver 2.4-7.2A 18-80VAC or 36-110VDC DM860T
£43.00
Transformer 48v DC for stepper driver
3201 2ZEU double row angular contact bearing
Stepper driver board
Stepper Motor Driver Controller 12-24V PWM Pulse Signal Generator Speed Control
£5.99

[@alun7006]

This is fascinating - do you have the build procesd documented anywhere? I have one of these lathes to get back up and running and this looks like a great set of upgrades!

[@johngreathead5733]

I am part way through a rebuild of one of these lathes that was given to me, Like Alun7006 I would like some more detail as to the lathe drive mods, a full list of parts would me appreciated, importantly thanks for the impetus. I have 2 so plenty to play with. Great stuff.

[@john2478]

John, glad that my efforts have interested the 2 of you. I didn’t do drawings as I had to tailor them to fit. Things like the plastic plate at the rear of the lathe that secures the lead screw is a good example. The plastic has large holes in it that are counterbored oversized. It was not easy to come up with an accurate part without doing the same thing and making them a sloppy fit. It is also possible that the lead screw is not aligned accurately. I will give it some thought though. The rear plate should never have been plastic in the first place. I will post something in the next few days. John

[@johngreathead5733]

Hi John, thanks for responding so quickly, I need to start somewhere, so up the front end we have a DC motor, the type you have mentioned, what size pulley and belts, assuming that you are using the original main shaft pulley. The use of a stepper motor to drive the lead screw is ideal, mainly because the lead screw is a right hand thread and therefore the handle turns 'the wrong way' so to speak. your adding of the CNC controller adds a new dimension, importantly the fact that you can switch this out and control it 'manually' through the powered stepper is so versatile, your encoder set up is of interest, I did look at the site, most interesting. I am not either a computer whizz nor am I electrically minded so this is an adventure for me. trust you don't mind me asking too many question. Best regards, John. @@john2478

[@john2478]

@@johngreathead5733 John I can help with a few details now.I used the standard spindle pulley with its securing collar and key. For the motor I made up a pulley from 40mm rod. The inside of the recess for the belt is 27mm. The motor came with a sprocket on it on a short stubby shaft. The motor shaft had a 8mm thread on it and there was just enough length to fit the recess for the belt as well as a short length on the outside of the pulley through which I drilled and tapped m3 to help secure the pulley. I also fitted a lock nut tightened well up using the outer 40mm of the pulley to hold the shaft. I made my pulley from mild steel but you could use aluminium. The resulting speed with the smaller leadscrew pulley is 250rpm to 1285 rpm. I just checked and the larger diameter pulley on the spindle. The motor uses the supplied mount and I fitted it to a 6mm aluminium plate. This plate has 8mm stand off collars between the old mount position and the new engine mount. I chose to fit the front end of the motor with a hinge so I could loosen just 2 bolts to remove the belt. The belt I use is 8mm 375mm optibelt. If you wanted to use the large spindle pulley then it would need 355mm belt. However that raises the lower end speed as the range is now 400-1700 rpm. Personally I would opt for the smaller pulley as I did, or even make up a new pulley for the spindle of slightly smaller size. John

[@johngreathead5733]

Thanks John, some parts on order, a little confused that if you use the large spindle pulley then the belt would be shorter by 20mm, its been a long day and I might be missing something! I thinks that I will use your suggested set up, any form of belt tensioner? Ta John. @@john2478

[@john2478]

John I didn't fit a belt tensioner I felt unnecessary complication plus there is not a lot of room. The 2 securing screws have stand offs and the belt could be tensioned by turning a little off these if necessary. You need a shorter belt with the smaller pulley option hence it is 355mm and for the larger one it is 375mm. I will have a go at measuring some of the parts. I shall have to make up a new video. Not sure if I will do cnc drawings or just sketch them with dimensions.John

[@mervynprice7009]

I always ask one question when I watch people taking deeper & deeper cuts. Why? To me a Lathe has a happy point where it enjoys the cutter depth. Only a fool takes deeper cuts than this happy depth. You are there to enjoy working your Lathe, so why would you push it beyond its happy working. Going beyond this happy point is not going to be a happy time for you so why are you doing it. Just grow up & when your Lathe is running nice & happy just enjoy it.

[@john2478]

Mervyn I was curious to see what this lathe was capable of. I would probably stick to 0.4mm in daily use as the lathe could cope with this quite comfortably. I do not like to drive things to the point where a tip digs in and it stops that lathe or mill. Frankly this little lathe has impressed me with what it is capable of. John